Effects of Cadmium and Salicylic Acid on Growth, Cd Accumulation and Photosynthesis of an Energy Crop, Castor Bean

The possible mediatory role of salicylic acid (SA) in protecting plants from cadmium (Cd) toxicity was investigated. Increasing Cd concentrations caused a decrease in shoot and root biomass, chlorophyll (a, b) and carotenoids content, and photosynthetic rate in plants. Pretreatment with 500 μM SA did not change the plant growth, Cd accumulation, and water relation in Cd-stressed plants. Moreover, it can aggravate Cdinduced decline of photosynthetic rate in plants exposed to 25 mg Cd kg-1 soil, by reducing the stomatal conductance and pigment contents. These results suggest that exogenous SA may not improve the tolerance of the castor bean plants to the Cd toxicity under soil conditions.